 /*
  * $Header: /cvshome/build/org.osgi.service.event/src/org/osgi/service/event/EventHandler.java,v 1.10 2006/07/11 16:43:59 hargrave Exp $
  *
  * Copyright (c) OSGi Alliance (2005, 2006). All Rights Reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  * http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 package org.osgi.service.event;

 /**
  * Listener for Events.
  *
  * <p>
  * <code>EventHandler</code> objects are registered with the Framework service
  * registry and are notified with an <code>Event</code> object when an
  * event is sent or posted.
  * <p>
  * <code>EventHandler</code> objects can inspect the received
  * <code>Event</code> object to determine its topic and properties.
  *
  * <p>
  * <code>EventHandler</code> objects must be registered with a service
  * property {@link EventConstants#EVENT_TOPIC} whose value is the list of
  * topics in which the event handler is interesed.
  * <p>
  * For example:
  *
  * <pre>
  * String[] topics = new String[] {EventConstants.EVENT_TOPIC, &quot;com/isv/*&quot;};
  * Hashtable ht = new Hashtable();
  * ht.put(EVENT_TOPIC, topics);
  * context.registerService(EventHandler.class.getName(), this, ht);
  * </pre>
  * Event Handler services can also be registered with an {@link EventConstants#EVENT_FILTER}
  * service propery to further filter the events. If the syntax of this filter is invalid,
  * then the Event Handler must be ignored by the Event Admin service. The Event Admin
  * service should log a warning.
  * <p>
  * Security Considerations. Bundles wishing to monitor <code>Event</code>
  * objects will require <code>ServicePermission[EventHandler,REGISTER]</code>
  * to register an <code>EventHandler</code> service. The bundle must also have
  * <code>TopicPermission[topic,SUBSCRIBE]</code> for the topic specified in the
  * event in order to receive the event.
  *
  * @see Event
  *
  * @version $Revision: 1.10 $
  */
 public interface EventHandler {
     /**
      * Called by the {@link EventAdmin} service to notify the listener of an event.
      *
      * @param event The event that occurred.
      */
     void handleEvent(Event event);
 }

